Disclosure of Invention
The invention provides an intelligent transformer formed by mature and reliable devices, which can detect various parameters of a power grid and the intelligent transformer, and can make proper allocation on the output of the power grid and make corresponding protection measures on the safety of the intelligent transformer.
In order to achieve the purpose, the invention adopts the technical scheme that:
an intelligent transformer is designed, and comprises an oil-immersed transformer, a master station with a monitoring and scheduling platform function, a circuit breaker and an intelligent terminal controller, wherein the master station is communicated with the circuit breaker and the intelligent terminal controller through communication interfaces respectively; and,
the intelligent terminal controller is provided with a plurality of input ports and a plurality of output ports, the input ends of the intelligent terminal controller are connected with,
the transformer group comprises four transformers, wherein the four transformers respectively detect three live wires and one zero wire of a three-phase four-wire power grid, the transformation ratio of the transformers connected with the three live wires is configured according to the rated current of the rated capacity of the transformer, and the transformation ratio of the transformers connected with the zero wire is configured according to 25% of the rated current of the rated capacity of the transformer;
a temperature sensor for measuring the temperature of the transformer oil, wherein the temperature sensor is positioned at the top of an oil tank of the oil-immersed transformer; extending into oil for more than 50 mm.
The pressure sensor is used for measuring the oil gas pressure of the transformer and is positioned at the top of an oil tank of the oil-immersed transformer;
the output end of the power supply is connected with the power supply,
an electronic tap changer controlling a high-voltage side of the oil-immersed transformer;
a reactive compensation system which consists of 6-12 paths of self-healing parallel capacitors and is divided into three groups for common compensation and one group for compensation, wherein the compensation capacity is configured according to 20 percent of the rated capacity of the transformer, the input and the cut of each path of self-healing parallel capacitors pass through a miniature circuit breaker and a solid-state relay, and the triggering point of the solid-state relay is connected to the output end of the intelligent terminal controller;
the safety valve is arranged at the top of an oil tank of the oil-immersed transformer and is communicated with the intelligent terminal controller by adopting a passive contact;
the two ends of the breaker are respectively connected with the incoming line and the outgoing line of the oil immersed transformer, the breaker is provided with an electric operating mechanism and receives wireless communication instruction action, and meanwhile, the breaker has a load short circuit protection function and is provided with an alarm contact to feed back information to a terminal.
The input end of the intelligent terminal controller is also connected with a gas relay, and the gas relay is communicated with the intelligent terminal controller through a passive dry contact.
The master station employs a processor with interactive functionality.
The circuit breaker adopts 3VL series or CMZ2A series circuit breaker; the intelligent terminal controller adopts HJ3000 PD.
And the communication interface adopts RS 485.
The temperature sensor is composed of two paths of PT100 type oil temperature sensors which enter oil by 50-100 mm; the pressure sensor adopts a pressure relay and adopts a passive contact; the safety valve adopts a pressure releaser; the oil immersed transformer is provided with a sealed moisture absorber, and the bottom of an oil tank of the oil immersed transformer is provided with a sampling valve and a large oil discharge valve of insulating oil.
For safe, stable and efficient operation of the transformer, the main station protects the transformer through the circuit breaker and the intelligent terminal controller in the following way,
the low-voltage side working phase current is allowed to run for a long time when the current exceeds 1.2 times of the rated current, the master station sends out an alarm signal when the current exceeds 1.5 times of the rated current, the HJ3000PD instructs the low-voltage circuit breaker to open the switch when the current is not reduced to 1.15 times of the rated current after the low-voltage side working phase current continuously runs for 4 hours, and the transformer is started after the transformer stops running for 5 seconds.
And secondly, when the working phase current of the low-voltage end exceeds 2 times of the rated current, the HJ3000PD sends an alarm signal, when the working phase current of the low-voltage end does not fall to 1.15 times of the rated current within 30 minutes, the HJ3000PD instructs the low-voltage circuit breaker to open, and the transformer stops running for 5 seconds and then starts.
Controlling 380V of line voltage at the low-voltage end of the transformer within the range of 410V-350V,
when the voltage is higher than 410V, the master station sends an alarm signal, when the voltage is higher than 660V, the alarm signal is sent again, the voltage does not drop below 410V within 30 minutes, the HJ3000PD instructs the low-voltage circuit breaker to open the switch, the transformer stops running, when the voltage returns to normal, the HJ3000PD instructs the low-voltage circuit breaker to close the switch, and the transformer returns to running;
when the voltage is lower than 350V, the main station sends out an alarm signal, when the voltage is lower than 320V, the alarm signal is sent out again, the voltage does not rise to 350V within 30 minutes, the HJ3000PD instructs the low-voltage circuit breaker to be opened, the transformer stops running, when the voltage returns to normal, the HJ3000PD instructs the low-voltage circuit breaker to be closed, and the transformer returns to running.
Fourthly, the voltage 220V at the low-voltage end of the transformer is controlled within the range of 230V-180V,
when the voltage is higher than the 230V and higher than the voltage, the master station sends out an alarm signal, when the voltage is higher than 380V, the alarm signal is sent out again, after 30 minutes, the phase voltage does not drop to 230V, the HJ3000PD instructs the low-voltage circuit breaker to open the brake, the transformer stops running, when the voltage returns to normal, the HJ3000PD instructs the low-voltage circuit breaker to close the brake, and the transformer returns to running;
when the voltage is recovered to be normal, the HJ3000PD instructs the low-voltage circuit breaker to be switched on, and the transformer recovers to operate.
When the voltage of the transformer is reduced due to the reduction of the power factor caused by the lack of reactive power, the master station controls the reactive power compensation system to be put into the compensation capacitor through HJ3000PD to increase the power factor in time, thereby increasing the voltage.
Sixthly, when the reactive power energy required by the operation of the transformer is sufficient and the power supply voltage fluctuates, the master station timely instructs the HJ3000PD to start the electronic tap switch to adjust the power supply voltage.
And the power supply frequency of the power grid is standard 50Hz, the power supply frequency is controlled within the range of 52 Hz-48 Hz, the master station sends an alarm signal when the power supply frequency is higher than 60Hz, the alarm signal is sent again when the power supply frequency is higher than 100Hz, the HJ3000PD instructs the low-voltage circuit breaker to open the switch, the transformer stops running, the line frequency returns to normal after the situation is processed, the master station sends a signal to HJ3000PD, and the HJ3000PD instructs the low-voltage circuit breaker to close the switch, and the transformer resumes running.
Eighthly, when the line voltages of the harmonic voltages of the 3 th, 5 th and 7 th order at the low-voltage end are less than or equal to 19 volts and the phase voltage is less than or equal to 11 volts, the master station sends out an alarm signal, and when no improvement exists for 10 minutes, HJ3000PD instructs the low-voltage circuit breaker to open the brake, and the transformer stops running; the transformer resumes operation when the harmonic content falls below the rated value of 5%.
Ninthly, the three-phase unbalance of the transformer can be monitored in real time through a zero-sequence current transformer for detecting the zero line, and when the three-phase unbalance exceeds 25%, the HJ3000PD instructs the low-voltage outgoing line breaker to open the brake, so that the transformer stops running; and informing a power utilization manager of adjusting the load in time through a short message, and restoring the operation of the transformer after the normal operation.
The method comprises the steps that average power failure time of low-voltage users, namely AIAC, average power failure times of the low-voltage users, namely AITC, average power utilization reliability of the low-voltage users, namely RS, are counted in real time at the capacitor (R) HJ3000PD, the average power failure times of the low-voltage users, namely AITC, average power utilization reliability of the low-voltage users, namely RS are transmitted to a master station periodically, the master station stores and keeps statistical data for.
The HJ3000PD monitors the three-phase voltage value in the power grid in real time through a transformer group, when the voltage of any phase is reflected to be 0V (volt), a master station sends out a phase-lack alarm signal, the HJ3000PD instructs a low-voltage circuit breaker to open the brake within 10 seconds, and the transformer stops running.
By utilizing the short-circuit protection function of the circuit breaker, when the load is short-circuited, the load is cut off within 2 seconds, the circuit breaker inputs short-circuit information into the HJ3000PD in time, and the HJ3000PD transmits the information to the main station and informs that the opening is short-circuit protection.
The method comprises the steps that the main station normally operates when the temperature value of transformer oil is set to be less than 98 ℃, an alarm is given and indoor cooling facilities are started when the temperature value is greater than 105 ℃, the alarm time limit is 4 hours, the temperature is reduced to 98 ℃ in the time period, the alarm and cooling facilities are stopped, the main station signals HJ3000PD when the temperature is still greater than 105 ℃ in the time period, the HJ3000PD instructs a low-voltage circuit breaker to open and close, the transformer stops operating, and the HJ3000PD instructs a circuit breaker to close when the temperature of the transformer oil is reduced to 98 ℃, so that the transformer resumes operating.
When the oil-immersed transformer is installed indoors, when the indoor gas concentration reaches 250-300mL, the gas relay is connected with the HJ3000PD terminal controller, and the HJ3000PD informs the master station to give an alarm and start an indoor ventilation and exhaust facility.
When the pressure of the transformer oil exceeds 40KPa, the passive contact of the pressure relay is switched on, a signal is transmitted to HJ3000PD, at the moment, the HJ3000PD instructs the low-voltage circuit breaker to open, the transformer stops running, and the pressure releaser is opened after 4 seconds to spray oil gas for pressure reduction.
The invention has the beneficial effects that: and detecting almost all parameters in the power grid by using the four transformers, and reasonably allocating the power grid through the self-healing parallel capacitor and the electronic tap switch according to a detection result. And detecting the working condition of the user by using a sensor, and taking emergency measures to protect the safety of the user in due time. The functions are realized by adopting a central processing unit with an interactive function to match with an HJ3000PD terminal controller and a 3VL series circuit breaker, and high performance, high reliability and low manufacturing cost can be realized.
Detailed Description
An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.
Referring to fig. 1, in the intelligent transformer of the present invention, the transformer is an oil-immersed transformer 1, and the intelligent transformer is equipped with a master station 2 having an interaction function and a control function, a circuit breaker 3, and an intelligent terminal controller 4. The main station 2 communicates with the circuit breaker 3 and the intelligent terminal controller 4 through an RS485 interface, so that the intellectualization of the transformer is formed, and meanwhile, a device with detection and execution functions is also arranged:
1. the mutual inductor group 5 connected with the intelligent terminal controller 4 detects A, B, C three-phase and N-phase currents in a three-phase four-wire power grid, the intelligent terminal controller 4 monitors the running state of the transformer in real time according to signals fed back by the mutual inductor group 5, the signals comprise analog signals such as voltage, current, frequency, harmonic waves, active power, reactive power, power factors, three-phase current unbalance, power failure time and times and the like, and the signals are transmitted to the main station 2 through an RS485 interface after being subjected to digital conversion.
2. The intelligent terminal controller 4 is connected with an electronic tap switch 6, and the intelligent terminal controller 4 switches the high-voltage side electronic tap switch 6 according to the change of the voltage value after reactive compensation, so that the stability of the low-voltage power supply voltage is ensured.
3. The intelligent terminal controller 4 is connected with a reactive power compensation system 7, the reactive power compensation system 7 is composed of a self-healing parallel capacitor 18, a miniature circuit breaker 19 and a solid state relay 20, and the intelligent terminal controller 4 controls the solid state relay 20 to be switched in or switched off through a DC24V active contact to compensate the deficiency of reactive current according to the change of power factors.
4. A temperature sensor 8 is arranged in the oil-immersed transformer 1, and the temperature sensor 8 is connected to the intelligent terminal controller 4 to provide the temperature of transformer oil.
5. A pressure sensor 9 is arranged in the oil-immersed transformer 1, the pressure sensor 9 is connected to the intelligent terminal controller 4, and the pressure sensor 9 is used for monitoring the thermal expansion pressure of transformer oil; meanwhile, a gas sensor is also arranged on the oil immersed transformer installed indoors, so that the light and heavy gas quantity can be monitored, and the oil immersed transformer is used for fire prevention.
6. Still be equipped with relief valve 10 in the oil-immersed transformer 1, relief valve 10 is controlled by intelligent terminal control ware 4, opens the relief valve blowout oil gas when the inside oil gas pressure of transformer reaches the limit and guarantees transformer safety for it is explosion-proof.
The structure of the intelligent transformer will be described in detail with an embodiment, in which the transformer has a specification of S11Z-KVA-10 KV/0.4 KV-W.
Consists of the following components: s11 the oil-immersed transformer body, the integrated intelligent box and the external main station 2 perform MODBUS universal protocol communication through RS-484 communication interfaces. The master station 2 adopts an industrial personal computer.
The intelligent box contains: the intelligent terminal comprises a circuit breaker 3, an intelligent terminal controller 4, a mutual inductor group 5, a self-healing parallel capacitor 18, a power supply box 21, a communication terminal 16, an electronic tap switch 6, a miniature circuit breaker 19, a solid-state relay 20, a lightning arrester 17 and the like. Wherein,
1. the circuit breaker 3 is an electrically operated circuit breaker with communication interface, and adopts 3VL (German Siemens) or CMZ2(very well-known in China) on-load controllable circuit breakers.
2. The intelligent terminal controller 4 adopts an HJ3000PD intelligent terminal controller, monitors the running state of the transformer in real time according to signals fed back by the transformer group 5, converts analog signals such as voltage, current, frequency, harmonic waves, active power, reactive power, power factors, three-phase current unbalance, power failure time and times and the like into digital signals, and transmits the digital signals to the main station 2 through an RS485 interface.
3. The transformer group 5 is four current transformers 13 which respectively detect A, B, C three-phase lines and N lines, the transformation ratio of the current transformers 13 is configured according to the rated current of the rated capacity of the transformer, and the N phase is configured according to 25% of the rated current.
4. The eight self-healing parallel capacitors 18, the six miniature circuit breakers 19 and the twelve solid-state relays 20 form a reactive power compensation system 7 with three groups of compensation and one group of compensation.
5. The power box 21 contains 24V dc power.
6. The electronic tap changer 6 is a +/-2 multiplied by 2.5% 5-bit electronic on-load tap changer composed of high-power silicon controlled rectifiers, is used for controlling the high-voltage side of a transformer, introducing a trigger signal line of the silicon controlled rectifiers of the tap changer into HJ3000PD, transmitting a signal to the main station 2 by the HJ3000PD, setting a starting and closing program by the main station 2, and ensuring the stability of output voltage at the low-voltage side.
7. The lightning arrester 17 adopts three zinc oxide lightning arresters, and can prevent lightning overvoltage.
8. The communication terminal 16 connects the master station 2, the circuit breaker 3, and the intelligent terminal controller 4.
In the transformer body:
1. the top of the transformer is provided with two PT100 type oil temperature sensors, the sensors enter oil by 50-100 mm, the upper limit point of the oil temperature is connected by adopting a passive contact, a signal line is connected with an HJ3000PD terminal controller, the HJ3000PD transmits oil temperature signals at the top of the transformer to the master station 2 in a communication mode, and the master station 2 sets a protection value.
2. The pressure relay is arranged, the upper limit value of the pressure relay is uploaded to HJ3000PD in a passive dry contact mode, then signals are transmitted to the main station 2 through HJ3000PD, and the main station 2 instructs the circuit breaker 3 to control the operation of the transformer.
3. And a pressure releaser is installed, and the action delay of the pressure releaser is more than 5 seconds after the pressure relay, namely, the oil injection is ensured to release the pressure after the transformer stops running.
4. The sealed moisture absorber is arranged, so that the water content in the insulating oil is not over standard.
5. The bottom of the oil tank is also provided with a sampling valve and a larger oil discharge valve for insulating oil, so that the insulating property of the oil can be checked conveniently, and the oil can be changed during maintenance.
Main website 2, circuit breaker 3, intelligent terminal control ware 4 to and have the device collaborative work that detects and carry out the function, operate under the control program that main website 2 set for, guarantee transformer safety, work steadily:
1. over-current (overload) protection.
1.1. When the working phase current of the low-voltage side exceeds 1.2 times of rated current, the low-voltage side is allowed to operate for a long time, when the working phase current exceeds 1.5 times of the rated current, the master station 2 sends out an alarm signal, when the working phase current continuously operates for 4 hours and does not drop to 1.15 times of the rated current, HJ3000PD instructs the low-voltage circuit breaker 3 to open the brake, and the transformer stops operating for 5 seconds and then starts.
1.2. When the working phase current of the low-voltage side exceeds 2 times of rated current, HJ3000PD sends out an alarm signal, when the working phase current of the low-voltage side does not fall to 1.15 times of rated current within 30 minutes, HJ3000PD instructs the low-voltage circuit breaker 3 to open, and the transformer stops running for 5 seconds and then starts.
2. Over-voltage and under-voltage protection.
2.1. The voltage standard of the low-voltage side wire of the transformer is 380V, and is controlled in a range of (410V-350V).
When the voltage is higher than 410V, the main station 2 sends an alarm signal, when the voltage is 660V, the alarm signal is sent again, the HJ3000PD instruction low-voltage circuit breaker 3 is not dropped below 410V within 30 minutes, the transformer stops running, when the voltage returns to normal, the HJ3000PD instruction low-voltage circuit breaker 3 is switched on, and the transformer returns to running.
When the voltage is lower than 350V, the main station 2 sends out an alarm signal, when the voltage is 320V, the main station sends out the alarm signal again, the HJ3000PD does not rise to 350V or more within 30 minutes to instruct the low-voltage circuit breaker 3 to be switched off, the transformer stops running, when the voltage returns to normal, the HJ3000PD instructs the low-voltage circuit breaker 3 to be switched on, and the transformer returns to running.
2.2. The voltage of the low-voltage side phase of the transformer is 220V, and is controlled within the range of (230V-180V).
The main station 2 sends out an alarm when the voltage exceeds 230V, and sends out an alarm signal when the voltage is higher than 380V, after 30 minutes, when the phase voltage does not drop to 230V, the HJ3000PD instructs the low-voltage circuit breaker 3 to open, the transformer stops running, when the voltage returns to normal, the HJ3000PD instructs the low-voltage circuit breaker 3 to close, and the transformer resumes running.
The master station 2 sends out an alarm when the voltage is lower than 180V, and sends out an alarm signal when the voltage is lower than 170V, when the voltage does not rise to 180V within 30 minutes, the HJ3000PD instructs the low-voltage circuit breaker 3 to open, the transformer stops running, and when the voltage returns to normal, the HJ3000PD instructs the low-voltage circuit breaker 3 to close, and the transformer returns to running.
2.3. When the transformer runs, the power factor is reduced due to the lack of reactive electric energy, so that the voltage at the low-voltage end is reduced, the reactive compensation system 7 can dynamically track and put into operation at the moment, the power factor is timely improved, the voltage is timely increased, the system is an effective energy-saving and emission-reducing system, the active electric energy loss is saved, and the quality of the power supply voltage is ensured.
2.4. When the transformer needs sufficient reactive power energy and the power supply voltage fluctuates, the master station 2 timely instructs the HJ3000PD to start the electronic on-load tap-changer of the transformer, and the power supply voltage is adjusted in time.
3. And power supply frequency variation overrun protection.
3.1. The power supply frequency standard of a power grid is 50Hz, the power supply frequency standard is controlled within the range of 52 Hz-48 Hz, the master station 2 sends an alarm signal when the power supply frequency is higher than 60Hz, the alarm signal is sent again when the power supply frequency is 100Hz, the alarm signal is not processed for 2 hours, the HJ3000PD instructs the low-voltage circuit breaker 3 to be opened when the frequency is still 60Hz, the transformer stops running, the master station 2 sends a signal after the situation is processed, the HJ3000PD instructs the low-voltage circuit breaker 3 to be closed, and the transformer resumes running.
4. Harmonic distortion rate protection.
4.1. The allowable value of the voltage total harmonic distortion of a low-voltage 380V power grid is 5%, the voltage between opposite phases of the low-voltage power grid is 380V, the voltage between opposite grounds is 220V, the distortion value between phases is 19V, and the distortion value of the opposite grounds is 11V.
4.2. When the line voltage of 3, 5 and 7 subharmonics of the low-voltage end is less than or equal to 19 volts and the phase voltage is less than or equal to 11 volts, the main station 2 sends out an alarm signal, when the low-voltage end is not processed for 10 minutes, the HJ3000PD instructs the low-voltage circuit breaker 3 to open the brake, the transformer stops running, and the power supply department needs to find out the reason and eliminate the reason.
5. And (4) three-phase load unbalance protection.
The three-phase unbalance calculation method comprises the following steps:
β% = [(Imax - Icp) ÷ Icp] × 100%
beta-unbalance degree, Imax-single-phase maximum current value, Icp-three-phase average current value
The neutral current value caused by three-phase unbalance must not exceed the rated current value of the single-phase winding by 25%.
The intelligent chamber HJ3000PD can monitor the zero sequence current value in real time through the N-phase current transformer, when the zero sequence current value exceeds the specified value, the HJ3000PD instructs the low-voltage outgoing line breaker 3 to open the brake, and the transformer stops running.
6. And power supply reliability.
6.1. The statistical calculation method comprises the following steps:
1) average power off time of low voltage user, recorded as AIAC
AIAC = ∑ (duration of power outage per time x number of power outages per time)/total number of hours of users/user
2) Average number of power failures of low voltage users, recorded as AITC
AITC = ∑ (number of power failures per household)/total number of users/(times/household)
3) Low voltage user power utilization reliability, recorded as RS
RS = (1-user average outage time < AIAC >/statistical period time) × 100%
6.2.HJ3000PD terminal controller can real-time accurate monitoring statistics above-mentioned data and regularly transmit to main website 2, and main website 2 keeps more than two years to the statistical data storage, can effectively compare the power supply reliability level of going through the year.
7. And (4) open-phase protection.
7.1. The three-phase power supply of the low-voltage distribution network is lack of one phase, the lack of the phase is extremely harmful to electrical equipment and a transformer, a A, B, C three-phase value can be monitored in real time by HJ3000PD in an intelligent room, the voltage of any phase is reflected to be 0V, the phase is absent, the master station 2 sends an alarm signal (informing that phase is absent), the HJ3000PD instructs the low-voltage outgoing line breaker 3 to open the brake within 10 seconds, the transformer stops running, and the transformer recovers running after the accident treatment is finished.
8. And (4) short-circuit protection.
8.1. The short circuit harm is very big, probably burns out the transformer in the twinkling of an eye, and this protection utilizes low voltage circuit breaker 3 to cut off the load in the twinkling of an eye (2 seconds), and circuit breaker 3 can be in time with short circuit information input HJ3000PD, and HJ3000PD can be with information transmission to main website 2 to inform this time separating brake is short-circuit protection.
8.2. The magnitude of short-circuit current is relevant with the grounding measure of transformer substation's ground system and transformer installation ground, and the breaking capacity of circuit breaker 3 is selected for use in this embodiment is 25 KA. (this value can be selected for each distribution system requirement).
And 9.S11Z type transformer oil top temperature protection.
The main station (2) sets a temperature control value: < 980C normal operation, < 1050And C, alarming. The alarm time is 4 hours, during which the temperature should drop to 98 deg.C0C, if the temperature is still 105 ℃ during the period0C, the master station 2 signals HJ3000PD, the HJ3000PD instructs the low-voltage circuit breaker 3 to open the brake, the transformer stops running, and when the temperature of the transformer oil is reduced to 980And in the C period, the HJ3000PD instructs the breaker 3 to be switched on, and the transformer recovers operation.
10. And (4) protecting the sudden accident.
Partial discharge or other external factors caused by short circuit of a single-phase winding of the transformer cause oil gas expansion of the transformer, when the pressure exceeds 40KPA, a passive contact of the pressure relay is switched on, a signal is transmitted to HJ3000PD, the HJ3000PD instructs the low-voltage circuit breaker 3 to be switched off, the transformer stops running, and after 4 seconds, the pressure safety valve 10 of the transformer is opened to spray oil gas for pressure reduction, so that explosion and combustion accidents are prevented, and the transformer is turned into maintenance.